1. Field of the Invention
The present invention relates to a recording medium transporting apparatus that transports sheet shaped recording medium, and more particularly relates to an improvement of a recording medium transporting apparatus that is provided in a recording medium ejection component of an ink jet recording apparatus or the like. The recording medium transporting apparatus according to a preferred embodiment of the present invention uses a rowel spur, which presses the recording medium and contacts the print surface of the recording medium.
2. Description of Related Art
Conventional recording medium (paper) transporting apparatus use a rowel spur because the ink that is recorded on the normal paper may not be completely dried. The apparatus uses a rowel spur to transport the recording medium by making point contact with the paper and transporting the paper.
This kind of rowel spur reduces the amount of ink adhering to the rowel spur. Retransfer of the ink from the rowel spur to the recording medium, and slippage between the recording medium and the rowel spur or smudging of ink that is not completely adhered to the recording medium are reduced by making the radius of curvature R of the tooth edge of the rowel spur 0.08 mm or less. Japanese Laid-Open Patent Publication No. 5-104798 shows a recording medium transportation apparatus having a rowel spur in which abrasion is decreased by increasing the hardness of the tooth edge by surface processing including plating or the like. Japanese Laid-Open Patent Publication No. 6-312866 suggests that to maintain a high quality image, the radius of curvature R of the tooth edge of the rowel spur should be 0.05 mm or less.
However, when the amount of ink deposited on the recording medium is increased or when the drying of the ink is delayed (slow absorption of the ink into the paper) as a result of a request to make the printed density higher, the amount of ink adhering to the rowel spur cannot be minimized by only reducing the radius of curvature of the conventional tooth edge. Technical problems encountered with conventional apparatus include the retransfer of ink from the rowel spur to the recording medium, the occurrence of slippage between the rowel spur and the recording medium, smudging of ink that is not completely adhered to the recording medium and other image quality problems. Furthermore, when the amount of ink adhering to the rowel spur is increased, the penetration of the leading tooth edge of the rowel spur into the paper is restricted, and the ability of the conventional apparatus to transport the paper is reduced.